I stumbled across this yesterday and could not leave it in the shop. This is what I think I know.
16ga, 76 cm barrels choked IM, weak blueing but no dents or dings, bright bores, marked PRIMA Krupp Stahl, ESSEN. Chambers measure about 2 5/8".
Non ejector, four lock ups, two under lugs, a concealed cross bolt, and a hidden fourth fastener. Approx. 80% scroll engraving with arcaded fences, scalloped receiver, and cocking indicators. Several of the screws have been turned, but no apparent damage. A sliver of wood is missing from the fore end and someone has added a 1/4" wood extension to the stock. Otherwise it appears original to me.
Steven Dodd Hughes describes a very similar gun in one of his books.
I would appreciate any information you can give me about the gun, the maker, etc. Thanks for the help.